| 3 | | The Specim OWL is a multiband thermal instrument covering the MWIR - LWIR bands |
| | 3 | The Specim OWL is a multiband thermal instrument covering [http://en.wikipedia.org/wiki/Infrared#Commonly_used_sub-division_schemeen.wikipedia.org/wiki/Infrared LWIR] (specifically 7.6 to 12.3 μm) with 103 bands. In combination with SWIR measurements, this range enables better classification of minerals, particularly silicates. |
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| | 5 | As with the [wiki:Sensors/Hawk], the detector technology is [http://en.wikipedia.org/wiki/Mercury_cadmium_telluride Mercury Cadmium Telluride], this time tuned for LWIR rather than SWIR. This means there may be a number of bad pixels that need to be masked out. The OWL has also been found to have "blinking" pixels (also called "naughty", as they're not reliably bad), which switch between two different levels during the capture - at the time of writing, these are masked out, though it is hoped that data can be recovered from them in future. |
| | 6 | |
| | 7 | In order to calibrate the sensor, a pair of black bodies can be mechanically moved in front of the sensor lens one by one and a capture made. Under normal operational conditions, this is done automatically at the end of every line, after the autodark (closed shutter dark frames) capture. The black bodies should generally be set to bracket the temperature range of interest. The sensor response has been rated as essentially linear. |
| | 8 | |
| | 9 | The instrument and, more importantly, measurements are vulnerable to water absorption, so a desiccant cartridge is used to maintain conditions internally. The system (detector and optics) is temperature stabilised |
| | 13 | Data quality and calibration/validation reports may be found in the [wiki:Reports] section. |
| | 14 | |
| | 15 | == Instrument parameters == |
| | 16 | |
| | 17 | All numbers provided by Specim 15 May 2014: |
| | 18 | |
| | 19 | || '''Measurement''' || '''Value''' || |
| | 20 | || Measured FOV (total) || 24.20 degrees || |
| | 21 | || Measured FOV (from centre) || -11.79 degrees, 12.41 degrees || |
| | 22 | || Paraxial FOV || -11.80 degrees, 12.39 degrees || |
| | 23 | || Sensor IFOV || 0.063 degrees or 1.103 mrad || |
| | 24 | || Lens focal length || 42.886 || |
| | 25 | || - Focal length evaluation wavelength || 10014.19nm || |
| | 26 | || Optical axes position (central pixel) || 187.7 || |
| | 27 | || Max distortion || 0.0755mm or 0.0210 degrees or 0.171% || |
| | 28 | |
| | 29 | Instrument type is "OWL3", serial number is ??????. The evaluation was made with an objective of type OLEL43, serial number 011402. |
| | 30 | |